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 A208188 Number of distinct n-colored necklaces with 7 beads per color. 2
 1, 1, 246, 19003476, 16875655269948, 90784545100668913392, 2041012695880532470281654960, 150277870737901828652705825755721760, 30495546426686489361833408314854897254404320, 14997592385781765578538605874290442908069285068834560 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Alois P. Heinz, Table of n, a(n) for n = 0..35 FORMULA a(n) = Sum_{d|7} phi(7/d)*(n*d)!/(d!^n*n*7) if n>0 and a(0) = 1. EXAMPLE a(0) =   1: the empty necklace. a(1) =   1: {0000000}. a(2) = 246: {00000001111111, ..., 01010101010101}. MAPLE with(numtheory); a:= n-> `if`(n=0, 1, add(phi(7/d) *(n*d)!/(d!^n *7*n), d={1, 7})): seq(a(n), n=0..12); CROSSREFS Row n=7 of A208183. Cf. A000010, A000142. Sequence in context: A229478 A289334 A251516 * A177212 A044983 A175043 Adjacent sequences:  A208185 A208186 A208187 * A208189 A208190 A208191 KEYWORD nonn AUTHOR Alois P. Heinz, Feb 24 2012 STATUS approved

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Last modified April 20 23:46 EDT 2021. Contains 343143 sequences. (Running on oeis4.)